ESPN's Adam Schefter reported via Twitter that Alonso tore his ACL and is expected to miss the entire 2014 season. According to Schefter's report, recovery time is expected to be 7-9 months.

The team has yet to confirm the exact nature of the injury.

In a press release from the team Tuesday, general manager Doug Whaley said, "We have learned tonight that Kiko Alonso injured his knee while working out in Oregon. We do not have the details at this point, but early indications are that it may be significant."

Alonso was already recovering from offseason hip surgery before he hurt his knee.

In organized team activities last month, the Bills revealed their intention to move Alonso to weakside linebacker in new defensive coordinator Jim Schwartz's 4-3 system. Last year, Alonso played every defensive snap, 1,145, at middle linebacker.

He did not fully participate in OTA workouts due to his hip rehab.

"It's been nice to get that time off and relax," he said last month. "Now it's time to get back to work. I feel great. I've had a great rehab, and I'm just trying to get stronger."

Schwartz added last month, "Even though Kiko hasn't been out here full time, he's been out there just doing a little bit with some individual and some 7-on-7 here and there. He's on the progression like a lot of other young guys."

In 2013, Alonso led the Bills with 159 tackles, which ranked third in the league. He made the league's all-rookie team and was finished behind only the New York Jets defensive end Sheldon Richardson in voting for Defensive Rookie of the Year.

Alonso, 23, was a second-round pick (46th overall) out of Oregon in 2013. The 6-foot-3, 238-pounder compiled two sacks, four interceptions, one forced fumble and four passes defensed as a rookie.

The highlight of Alonso's season might have been a 22-tackle performance in the Bills' 27-24 loss to the Cincinnati Bengals on Oct. 13.